In minimally invasive spine interventions, it is very important to localize the correct vertebral level for treatment. The interventions are usually performed under X-ray guidance, with the X-ray system offering only a limited field-of-view. However, only few vertebral levels can reliably be identified from their shape or the surrounding anatomy in such assembled image. Therefore, the vertebral level has to be identified by palpitation and counting of landmarks or from visually assessing projection images from the limited X-ray field-of-view. As a result, the process is complicated and error-prone.
In digital X-ray imaging, a composition of an image from sub-images is generally used to form a composite image of an elongate scene which is too long to be reproduced in one operation. Using a contemporary digital X-ray examination apparatus, it is difficult or even impossible to form an X-ray image of the complete region of the spinal column of the patient to be examined in one exposure. A number of successive X-ray images of portions of the region to be examined are formed, which images together cover the entire region. A method of this kind is also called the translation reconstruction technique and is known from EP 0 655 861 A1.
Further, US2011/0276179 A1 discloses designating beginning and end points of a desired AP radiograph. A robotic system can retrace this path obtaining a contiguous X-ray image. The entire scan can be displayed on a computer screen. A surgeon can designate one or more desired surgical levels in the displayed scan. A further robotic system may hold a marker in place over the designated vertebral body while a confirmatory radiograph is obtained.